The present invention relates to a feeder device for longitudinal wires in machines for manufacturing electrically welded metallic nets.
It is known that in order to produce electrically welded nets, a plurality of longitudinal metallic wires is fed in a parallel arrangement, and appropriate transverse metallic wires are welded to said longitudinal wires at uniform distances. The longitudinal wires to be fed are unwound from respective coils and undergo a straightening operation before welding.
In order to feed the longitudinal wires, apparatuses which supply said wires continuously to the welding machine are in widespread use; the welding machine welds the transverse wires in a uniform succession. After a portion of a metallic net of the required length has been produced, the longitudinal wires are cut.
However, the cutting operation causes the release of the tension induced in the longitudinal wires by the straightening operation. Accordingly, metallic nets thus manufactured have undue distortions.
In order to obviate this drawback, apparatuses with discontinuous operation have been proposed; these apparatuses feed the welding machine with a series of longitudinal wires which have been pre-cut to size and straightened. In this manner the uniformity of the manufactured net is ensured.
However, these apparatuses, by operating discontinuously, have relatively long downtimes, with a consequent decrease in the productivity of the machine. Furthermore, it is evident that these apparatuses lead to poor production flexibility, since in order to manufacture metallic nets of different lengths it is necessary to have in stock corresponding sets of longitudinal wires cut to size and straightened. This forces to hold in stock a large amount of metallic wires or, vice versa, to limit the types of production.